1. Field of the Invention
The present invention relates to a liquid ejection head and a liquid ejection apparatus, and more particularly to the configuration of removing so-called kogation on a heat acting portion in a liquid ejection head for ejecting liquid such as ink by causing heat to act on the liquid to generate bubbles.
2. Description of the Related Art
In a liquid ejection head having a system of using thermal energy generated by an electrothermal transducer element to generate bubbles in liquid such as ink to eject the liquid, so-called kogation occurs on a heat acting portion and thereby the heat conduction from the heat acting portion to the liquid becomes uneven. This may occasionally cause unstable ejection.
In this respect, Japanese Patent Laid-Open No. 2008-105364 discloses providing an area which includes a heat acting portion with an upper protective layer acting as an electrode for generating an electrochemical reaction with ink, allowing the surface of the upper protective layer to be eluted, and removing kogation on the heat acting portion. In this configuration, for the arrangement of electrodes to generate the electrochemical reaction, the upper protective layer on the heat acting portion is set as an anode and a layer formed on the same plane as the upper protective layer is set as a cathode. That is, the anode and the cathode are located in parallel on a substrate.